|I am having the same issue as well when looking at the Unique Website Visitors Map. There is also a pop up that asks if I am the owner of this site. When I click on this it shows "Troubleshooting|
Under certain circumstances, a darkened map, or 'negative' Street View image, watermarked with the text "for development purposes only", may be displayed. This behavior typically indicates issues with either an API key or billing. In order to use Google Maps Platform products, billing must be enabled on your account, and all requests must include a valid API key. The following flow will help you troubleshoot the issue."